U.S. EPA has followed the orders of Congress by taking action to limit air pollution that contributes to global warming, the Obama administration argued yesterday in a strongly worded brief that urges federal judges not to prevent the first nationwide greenhouse gas regulations from taking effect on Jan. 2.

More than 100 businesses, advocacy groups and states have filed lawsuits questioning the legality of the agency's climate rules, which are intended to reduce emissions of greenhouse gases from cars, light-duty trucks and stationary sources. In recent months, the challengers have asked the U.S. Circuit Court of Appeals for the District of Columbia to put the new regulations on hold as the court cases unfold.

EPA and the Justice Department were defiant in their response to those requests yesterday. The agency's critics are ignoring a 2007 Supreme Court ruling that required EPA to take action if it determined that carbon dioxide was a threat to human health and welfare, according to the 120-page brief, which was signed by Ignacia Moreno, the head of DOJ's Environment and Natural Resources Division.

"They essentially seek to stay the Clean Air Act itself," the brief says. "The court, however, cannot stay the Clean Air Act."

That is the crux of the argument being put forward by the Obama administration, which says it had no choice but to regulate greenhouse gases once EPA issued its "endangerment" finding. That decision, based on the conclusions of scientists in the United States and abroad, will be difficult to attack in court, experts say.

Within six months of the December 2009 decision, EPA finalized three other rules to determine how and when the agency would begin regulating carbon dioxide from light vehicles and facilities. More recently, the agency has proposed expanding the program to include heavy-duty trucks, buses and other large vehicles.

The regulations on power plants, factories and other high-emitting facilities have been challenged by some of the nation's most powerful industry groups, including the U.S. Chamber of Commerce and the National Association of Manufacturers. They have been joined by a slew of small-government advocacy groups and states such as Texas, which have described the regulations as an illegal power grab by EPA.

"If the EPA moves forward and begins regulating stationary sources, it will open the door for the agency to regulate everything from industrial facilities to farms to even American homes," said NAM President John Engler when the group asked for a stay of the stationary source regulations last month (Greenwire, Sept. 16).

The Obama administration says it has tried to avoid that outcome through the "tailoring rule," which limited new permitting requirements to the largest facilities. In their response yesterday, EPA and DOJ said it was telling that challengers attacked the tailoring rule, which was intended to avoid "the very regulatory burdens [they] abhor."

Many legal experts consider that rule the most vulnerable part of the agency's program, saying the agency's new thresholds for regulation seem arbitrary. But few people are willing to guess what might happen if a court were to strike down the rule.

Critics contend that the need for the tailoring rule demonstrates that the Clean Air Act was not intended to regulate greenhouse gases. EPA has admitted that following the letter of the law would lead to "absurd" results but argues that the Clean Air Act was intended to allow the agency to handle any type of air pollution.

It would be a more absurd violation of the Clean Air Act to ignore the harm caused by global warming and not regulate greenhouse gases at all, the administration argued yesterday.

The challengers "flail variously at EPA's four actions in an attempt to halt that which is imposed by operation of statute," the brief says. "But their efforts are for naught: their objection, at bottom, is not really to EPA's actions; rather, it is to the decisions Congress made and to the strict requirements Congress itself imposed on sources of air pollution."

Click here to read the administration's brief.